This invention relates to a machine for closing bags and such objects as sacks and tubes by means of wire clips which are placed in a U-shape around the gathered end or neck of the bags to be closed and then are bent together around this end.
The known clipping machines for securing a clip around the gathered ends or necks of bags and the like are usually provided with a fixed die, a guide which is set or directed towards the die in which the U-shaped clips with the parallel leg in front are pushed by a punch against the die, and a gate opening in which the gathered end of the bag to be closed can be moved up to the die and into the said guide. At the entrance end opposite to the die the gate is wide, so that the end of the bag to be closed can be inserted easily, and at the other end, it is narrow and closed by the stationary die. The narrow end is in the guide and is narrower than the space between the legs of the clips. Therefore, a clip pushed forward by the punch in the guide slides past with its legs on both sides of the bag end which is in the narrow end of the gate opening. With continued movement of the punch, the legs reach the die and are bent together by this, until the clip closes tightly and firmly around the bag end.
These known machines have the disadvantage that, after the clipping process, the end of the bag to be closed must be moved out of the gate opening in the opposite direction to the direction in which it was inserted. Therefore, they are not suited for automatic packaging units where it is desirable for the bags which are to be closed to be conveyed in a continuous movement in one direction by a conveyor.
An object of the invention is to create a clipping machine which can be used in automatic packaging units. A further object of the invention is to create a clipping machine of this kind which can be controlled automatically. A further object of the invention is to create a clipping machine which is controlled by the movement of the goods to be clipped.
These and other objects are achieved by providing a die in a machine of the type previously described which is movable between a first position, in which it closes the narrow end of the gate opening, ready to function, and a second position, in which the narrow end of the gate opening is open. When the die is in the first position, it is ready to close a bag. The end of the bag to be closed can be inserted in one direction into the gate opening. After this, the punch is set in motion and the clip is closed around the gathered end of the bag. Then the die is moved into the second position, so that the closed bag end can leave the gate opening at the end which was previously closed by the die. Therefore, it is not necessary for the bag end to reverse its direction of movement.
The punch is set in motion by means of a pneumatic, hydraulic or electric power drive, and in a similar manner, the die can also be moved by means of a power drive. Preferably, the controls of the two drives are linked with each other in such a way that the die is moved from the first into the second position as soon as the punch has completed its clipping movement.
This invention makes it possible to install a clipping machine in the conveyor line of an automatic packaging unit, so that the bags to be closed which follow the conveyor line can enter the gate opening at one end and leave it at the other end. It can be arranged for the control of the power drives for the punch and the die to be actuated automatically when a bag end to be closed approaches the gate opening, or enters into it, or passes any other certain point on the conveyor line.